Weight & Mass Units Encyclopedia
Understand the physical definitions, historical origins, SI base relationships, and exact conversion factors for every major global weight measurement.
International Metric System (SI) Units
5 UnitsKilogram
The kilogram is the primary unit of mass in the International System of Units (SI).
Gram
The gram is a fundamental metric unit of mass equal to one one-thousandth of a kilogram (10⁻³ kg).
Milligram
A milligram is equal to 1/1,000 of a gram and 1/1,000,000 of a kilogram.
Microgram
A microgram is equal to one-millionth of a gram (10⁻⁶ g) or one-billionth of a kilogram (10⁻⁹ kg).
Metric Ton (Tonne)
A metric ton (symbol: t, also spelled tonne) equals exactly 1,000 kilograms (1 megagram).
Imperial & US Customary Weight Units
5 UnitsPound
The pound (avoirdupois) equals exactly 0.45359237 kilograms and 16 ounces.
Ounce
The avoirdupois ounce equals 1/16 of a pound or exactly 28.349523125 grams.
Stone
The stone is an imperial unit of mass equal to 14 pounds or approximately 6.3503 kilograms.
US Ton (Short Ton)
A US short ton equals exactly 2,000 pounds (907.18474 kg).
Long Ton (Imperial Ton)
An Imperial long ton equals exactly 2,240 pounds (1,016.0469 kg).